Brihat Parashara Hora Shastra
शुभाशुभं वदेत् पित्रोर्जीवनं मरणं तथा। एवं निषेकलग्नेन सम्यग् ज्ञेयं स्वकल्पनात्॥ ३०॥
One can also guess with the help of Nishek Lagn effects, like longevity, death etc. of the parents.
english translation
zubhAzubhaM vadet pitrorjIvanaM maraNaM tathA। evaM niSekalagnena samyag jJeyaM svakalpanAt॥ 30॥
hk transliteration by Sanscript